ng-cross-control-validation — Angular Cross-Control Validator

A lightweight and flexible cross-field validation library for Angular Reactive Forms. Easily handle advanced validation scenarios where one form control's state or validity depends directly on the value of another.

npm install ng-cross-control-validation

• ⚡️ Reactive: Automatically re-evaluates when dependent controls change.
• 📦 Lightweight: Zero external dependencies (only Angular peer dependencies).
• ⚙️ Modern: Full support for Angular 17 and above (including standalone components).

Usage

import {
  crossControlValidator,
  crossControlEnabler,
} from 'ng-cross-control-validation';

crossControlValidator

Creates a cross-field validator that validates one control based on the value of another control.

const form = this.fb.group({
  subscriptionType: ['', Validators.required],
  discountCode: [
    '',
    [crossControlValidator('subscriptionType', (type: string) => type === 'premium')]
  ]
});

crossControlEnabler

Dynamically enables or disables a form control based on a specific value of another control.

const form = this.fb.group({
  feesRateAlignment: ['', [Validators.required]],
  feesRateAlignmentPolicy: ['', [
    crossControlEnabler('feesRateAlignment', (value) => value === 'default')
  ]]
});

Examples

Explore the Example App for full implementation use-cases.